JP4609098B2 - Process for oxidizing object, oxidation apparatus and storage medium - Google Patents

Process for oxidizing object, oxidation apparatus and storage medium Download PDF

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JP4609098B2
JP4609098B2 JP2005032341A JP2005032341A JP4609098B2 JP 4609098 B2 JP4609098 B2 JP 4609098B2 JP 2005032341 A JP2005032341 A JP 2005032341A JP 2005032341 A JP2005032341 A JP 2005032341A JP 4609098 B2 JP4609098 B2 JP 4609098B2
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鈴木　　啓介
俊之 池内
公也 青木
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/10—Oxidising
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    • C23C8/10—Oxidising
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    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
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Description

本発明は、半導体ウエハ等の被処理体の表面に対して酸化処理を施す被処理体の酸化方法、酸化装置及びこの酸化装置を制御するプログラムを記憶する記憶媒体に関する。   The present invention relates to an oxidation method for an object to be processed for oxidizing the surface of an object to be processed such as a semiconductor wafer, an oxidation apparatus, and a storage medium for storing a program for controlling the oxidation apparatus.

一般に、半導体集積回路を製造するためにはシリコン基板等よりなる半導体ウエハに対して、成膜処理、エッチング処理、酸化処理、拡散処理、改質処理等の各種の処理が行なわれる。上記各種の処理の中で、例えば酸化処理を例にとれば、この酸化処理は、単結晶或いはポリシリコン膜の表面等を酸化する場合、金属膜を酸化処理する場合等が知られており、特に、ゲート酸化膜やキャパシタ等の絶縁膜を形成する時に主に用いられる。   In general, in order to manufacture a semiconductor integrated circuit, various processes such as a film formation process, an etching process, an oxidation process, a diffusion process, and a modification process are performed on a semiconductor wafer made of a silicon substrate or the like. Among the various processes described above, for example, when an oxidation process is taken as an example, this oxidation process is known to oxidize the surface of a single crystal or a polysilicon film, or to oxidize a metal film, etc. In particular, it is mainly used when forming an insulating film such as a gate oxide film or a capacitor.

この酸化処理を行なう方法には、圧力の観点からは、略大気圧と同等の雰囲気下の処理容器内で行なう常圧酸化処理方法と真空雰囲気下の処理容器内で行なう減圧酸化処理方法とがあり、また、酸化に使用するガス種の観点からは、例えば水素と酸素とを外部燃焼装置にて燃焼させることによって水蒸気を発生させてこの水蒸気を用いて酸化を行なうウェット酸化処理方法（例えば特許文献１等）と、オゾンのみ、或いは酸素のみを処理容器内へ流すなどして水蒸気を用いないで酸化を行なうドライ酸化処理方法（例えば特許文献２等）とが存在する。   From the viewpoint of pressure, the oxidation treatment method includes a normal pressure oxidation treatment method performed in a treatment vessel under an atmosphere substantially equal to atmospheric pressure and a reduced pressure oxidation treatment method carried out in a treatment vessel under a vacuum atmosphere. In addition, from the viewpoint of the type of gas used for oxidation, for example, a wet oxidation method in which hydrogen and oxygen are burned in an external combustion device to generate water vapor and oxidation is performed using the water vapor (for example, a patent) Document 1 etc.) and a dry oxidation treatment method (for example, Patent Document 2 etc.) in which oxidation is performed without using water vapor by flowing only ozone or only oxygen into a processing vessel.

ところで、絶縁膜としては耐圧性、耐腐食性、信頼性等の膜質特性を考慮すると、一般的には、ドライ酸化処理により形成された物よりも、ウェット酸化処理により形成された物の方が比較的優れている。また、形成される酸化膜（絶縁膜）の成膜レートやウエハ面内の均一性の観点からは、一般的には、常圧のウェット酸化処理により形成された物は、酸化レートは大きいが、膜厚の面内均一性に劣り、減圧のウェット酸化処理により形成された物は、逆に酸化レートは小さいが膜厚の面内均一性に優れている、という特性を有している。   By the way, in view of film quality characteristics such as pressure resistance, corrosion resistance, and reliability, an insulating film is generally formed by a wet oxidation process rather than a dry oxidation process. It is relatively good. Further, from the viewpoint of the film formation rate of the oxide film (insulating film) to be formed and the uniformity within the wafer surface, in general, an object formed by normal-pressure wet oxidation treatment has a high oxidation rate. In addition, the in-plane uniformity of the film thickness is inferior, and the product formed by the wet oxidation treatment under reduced pressure has the characteristic that the oxidation rate is small but the in-plane uniformity of the film thickness is excellent.

従来にあっては、半導体集積回路のデザインルールがそれ程厳しくなかったことから、酸化膜が適用される用途やプロセス条件、装置コスト等を適宜勘案して、上述したような種々の酸化方法が用いられていた。しかしながら、最近のように線幅や膜厚がより小さくなってデザインルールが厳しくなると、それに従って、膜質の特性や膜厚の面内均一性等がより高いものが要求されるようになってきており、酸化処理方法では、この要求に十分に対応することができない、といった問題が発生してきた。   Conventionally, since the design rule of the semiconductor integrated circuit was not so strict, various oxidation methods as described above were used in consideration of the application, process conditions, equipment cost, etc. to which the oxide film is applied. It was done. However, as line width and film thickness become smaller and design rules become stricter as recently, higher quality and in-plane uniformity of film quality are required accordingly. However, there has been a problem that the oxidation treatment method cannot sufficiently meet this requirement.

また、ウェット酸化処理方法の例として例えば特許文献３に示すように、縦型の石英反応管内の下端にＨ２ ガスとＯ２ ガスとを別個に導入し、これを石英キャップ内に設けた燃焼部にて燃焼させて水蒸気を発生し、この水蒸気をウエハの配列方向に沿って上昇させつつ酸化処理を行なうようにした酸化装置も提案されている。しかし、この場合には、上記した燃焼部にてＨ２ ガスを燃焼させるようにしているので、例えば処理容器の下端では水蒸気リッチになり、そして、水蒸気が上昇するに従ってこれが消費されて処理容器の上端では逆に水蒸気不足の傾向となるので、ウエハ面上に形成される酸化膜の厚さがウエハの支持位置により大きく異なる場合が生じ、この酸化膜の厚さの面間均一性が劣化する場合もあった。 As an example of the wet oxidation treatment method, for example, as shown in Patent Document 3, H 2 gas and O 2 gas are separately introduced into the lower end of a vertical quartz reaction tube, and the combustion is provided in a quartz cap. There has also been proposed an oxidizer in which water vapor is generated by burning in a portion, and oxidation is performed while raising the water vapor along the arrangement direction of the wafer. However, in this case, since the H 2 gas is burned in the above-described combustion section, for example, the lower end of the processing vessel becomes water vapor rich, and this is consumed as the water vapor rises, and the processing vessel On the contrary, since the water vapor tends to be deficient at the upper end, the thickness of the oxide film formed on the wafer surface may vary greatly depending on the support position of the wafer, and the uniformity of the thickness of this oxide film deteriorates. There was a case.

また、他の装置例として例えば特許文献４に開示されているように、横型のバッチ式の反応管内に複数の半導体ウエハを並べて設置し、この反応管の一端側より、Ｏ２ ガスを導入したり、或いはＯ２ ガスとＨ２ ガスとを同時に導入したりして、減圧雰囲気下にて酸化膜を生成するようにした酸化装置も提示されている。しかし、この従来装置例の場合には、水素燃焼酸化法を用いて比較的高い圧力雰囲気下にて成膜を行っていることから、水蒸気成分が反応の主体となり、上述したように処理容器内のガス流の上流側と下流側との間での水蒸気の濃度差が大きくなり過ぎ、酸化膜の厚さの面間均一性が劣化する恐れがあった。
また更に、他の装置例として例えば特許文献５に開示されているように、ランプ加熱による枚葉式のプロセスチャンバ内に酸素ガスと水素ガスとを供給し、これらの両ガスをプロセスチャンバ内に設置した半導体ウエハ表面の近傍にて反応させて水蒸気を生成し、この水蒸気でウエハ表面のシリコンを酸化させて酸化膜を形成するようにした装置が示されている。 As another example of the apparatus, as disclosed in Patent Document 4, for example, a plurality of semiconductor wafers are arranged side by side in a horizontal batch type reaction tube, and O 2 gas is introduced from one end side of the reaction tube. There is also proposed an oxidation apparatus in which an O 2 gas and an H 2 gas are introduced simultaneously to generate an oxide film under a reduced pressure atmosphere. However, in the case of this conventional apparatus example, since the film formation is performed under a relatively high pressure atmosphere using the hydrogen combustion oxidation method, the water vapor component becomes the main component of the reaction, and as described above, The difference in water vapor concentration between the upstream side and the downstream side of the gas flow becomes too large, and the uniformity of the thickness of the oxide film may deteriorate.
As another example of the apparatus, as disclosed in, for example, Patent Document 5, oxygen gas and hydrogen gas are supplied into a single-wafer process chamber by lamp heating, and both these gases are put into the process chamber. An apparatus is shown in which water vapor is generated by reacting in the vicinity of the surface of an installed semiconductor wafer, and silicon on the wafer surface is oxidized with this water vapor to form an oxide film.

しかし、この装置例の場合には、ウエハから２０〜３０ｍｍ程度だけ離れたガス入口から酸素ガスと水素ガスとをプロセスチャンバ内に導入し、半導体ウエハ表面の近傍にてこれらの酸素ガスと水素ガスとを反応させて水蒸気を発生させて、しかもプロセス圧力も比較的高い領域で行うことから、膜厚の面内均一性に劣る恐れが生ずる、といった問題があった。
そこで、本出願人は、上記各問題点を解決するために特許文献６において、Ｏ２ などの酸化性ガスとＨ２ などの還元性ガスとを、それぞれ処理チャンバの上部と下部とに同時に供給して真空雰囲気下で反応させて酸素活性種と水酸基活性種とを主体とする雰囲気を形成し、この雰囲気中でシリコンウエハ等を酸化させる酸化方法を開示した。 However, in the case of this apparatus example, oxygen gas and hydrogen gas are introduced into the process chamber from a gas inlet separated by about 20 to 30 mm from the wafer, and these oxygen gas and hydrogen gas are introduced in the vicinity of the semiconductor wafer surface. Is generated in a region where the process pressure is relatively high, and there is a problem that the in-plane uniformity of the film thickness may be inferior.
The present applicant, in Patent Document 6 in order to solve the above problems, and a reducing gas such as an oxidizing gas and H 2, such as O 2, the upper and lower portions of the respective processing chambers simultaneously supply Then, an oxidation method is disclosed in which an atmosphere mainly composed of oxygen active species and hydroxyl active species is formed by reacting in a vacuum atmosphere, and a silicon wafer or the like is oxidized in this atmosphere.

この酸化方法を図１１を参照して簡単に説明する。図１１は従来の酸化装置を示す概略構成図である。図１１に示すように、この酸化装置２は外側周囲に抵抗加熱ヒータ４を配置した縦型の筒体状の処理容器６を有している。この処理容器６内には、その下方より昇降可能にロード・アンロードされるウエハボート８が設置されており、このウエハボート８にシリコン基板等よりなる半導体ウエハＷが多段に載置して保持されている。この処理容器６の下部側壁側には、Ｈ２ ガスを供給するＨ２ ガスノズル１０とＯ２ ガスを供給するＯ２ ガスノズル１２とが設けられており、処理容器６の上部には、図示しない真空ポンプ等に連結される排気口１４が設けられる。
上記両ノズル１０、１２より上記処理容器６内の下部に導入されたＨ２ ガスとＯ２ ガスの両ガスは、この処理容器６内で例えば１３３Ｐａ未満の圧力下で反応しつつ酸素活性種と水酸基活性種とを発生し、これらの活性種は処理容器６内を上昇しつつウエハＷの表面と接触してその表面を酸化することになる。 This oxidation method will be briefly described with reference to FIG. FIG. 11 is a schematic configuration diagram showing a conventional oxidation apparatus. As shown in FIG. 11, the oxidation apparatus 2 has a vertical cylindrical processing container 6 in which a resistance heater 4 is arranged around the outside. A wafer boat 8 that is loaded and unloaded so as to be able to be lifted and lowered from below is installed in the processing vessel 6, and semiconductor wafers W made of silicon substrates or the like are placed and held in multiple stages on the wafer boat 8. Has been. An H 2 gas nozzle 10 for supplying H 2 gas and an O 2 gas nozzle 12 for supplying O 2 gas are provided on the lower side wall side of the processing container 6, and a vacuum (not shown) is provided above the processing container 6. An exhaust port 14 connected to a pump or the like is provided.
Both the H 2 gas and the O 2 gas introduced into the lower part of the processing container 6 from the nozzles 10 and 12 react with the oxygen active species while reacting in the processing container 6 under a pressure of less than 133 Pa, for example. Hydroxyl active species are generated, and these active species come into contact with the surface of the wafer W while being raised in the processing vessel 6 to oxidize the surface.

特開平３−１４０４５３号公報Japanese Patent Laid-Open No. 3-140453 特開昭５７−１２３２号公報JP 57-1232 A 特開平４−１８７２７号公報Japanese Patent Laid-Open No. 4-18727 特開昭５７−１２３２号公報JP 57-1232 A 米国特許第６０３７２７３号明細書US Pat. No. 6,037,273 公開２００２−１７６０５２号公報Publication 2002-176052

上記したような特許文献１〜６に開示された酸化方法によれば、膜質特性が良好な酸化膜を形成でき、しかも、酸化膜の膜厚の面内均一性も高く維持することができた。ところで、最近にあっては、半導体ウエハの表面に異種の材料が露出している場合、このウエハ表面に上記したような膜質特性が良好な酸化膜を選択的に形成することが要請される場合が生じている。例えばフラッシュメモリのようにＯＮＯ膜のゲート構造を含む半導体集積回路を製造する場合には、半導体ウエハの表面にシリコン層とシリコン窒化層が共に露出した状態において、シリコン窒化層上にはＳｉＯ２ の酸化膜をできるだけ形成せずに特にシリコン層に上記したような膜質特性の良好な酸化膜を選択的に形成する必要がある。このような場合、前述したような酸素活性種と水酸基活性種とを単に用いた成膜方法では、酸化力が強いことからシリコン層上のみならず、酸化がし難いシリコン窒化層上もかなりの厚さでＳｉＯ２ 膜よりなる酸化膜が形成されてしまい、十分な選択酸化処理を実施することができない、といった不都合があった。 According to the oxidation methods disclosed in Patent Documents 1 to 6 as described above, an oxide film having good film quality characteristics can be formed, and the uniformity of the film thickness of the oxide film can be maintained high. . By the way, recently, when different materials are exposed on the surface of the semiconductor wafer, it is required to selectively form an oxide film with good film quality characteristics as described above on the wafer surface. Has occurred. For example, in the case of manufacturing a semiconductor integrated circuit including an ONO film gate structure such as a flash memory, in a state where both the silicon layer and the silicon nitride layer are exposed on the surface of the semiconductor wafer, SiO 2 is formed on the silicon nitride layer. It is necessary to selectively form an oxide film having good film quality characteristics as described above, particularly on the silicon layer, without forming an oxide film as much as possible. In such a case, the film forming method simply using the oxygen active species and the hydroxyl active species as described above has a strong oxidizing power, so that not only on the silicon layer but also on the silicon nitride layer that is difficult to oxidize. There is an inconvenience that an oxide film made of a SiO 2 film is formed with a thickness, and sufficient selective oxidation treatment cannot be performed.

この点について図１２を参照してより具体的に説明する。図１２はＯＮＯ膜よりなるゲート構造を有する半導体集積回路の製造工程の一部を示す図であり、例えばフラッシュメモリ用のゲート構造にあっては、シリコン基板１００上に、ゲート酸化膜１０２を介して例えば多結晶シリコンよりなる第１のゲート電極１０４を形成し、この第１のゲート電極１０４上に、シリコン酸化膜１０６、シリコン窒化膜１０８及びシリコン酸化膜１１０の３層構造よりなるＯＮＯ膜を有している（図１２（Ａ）参照）。   This point will be described more specifically with reference to FIG. FIG. 12 is a diagram showing a part of a manufacturing process of a semiconductor integrated circuit having a gate structure made of an ONO film. For example, in a gate structure for a flash memory, a gate oxide film 102 is interposed on a silicon substrate 100. For example, a first gate electrode 104 made of polycrystalline silicon is formed, and an ONO film having a three-layer structure of a silicon oxide film 106, a silicon nitride film 108, and a silicon oxide film 110 is formed on the first gate electrode 104. (See FIG. 12A).

そして、この素子の形成途中において、周辺回路素子のゲート酸化膜１１２（図１２（Ｂ）参照）を形成する場合には、上記ゲート酸化膜１１２の形成のために酸化処理を行なう。そして、その後に電極形成処理を行って、図１２（Ｃ）に示すように、フラッシュメモリ用の第２のゲート電極１１４を形成すると同時に、周辺回路素子用のゲート電極１１６を形成する。ここで図１２（Ｂ）に示す工程で酸化処理を行なう場合、酸素活性種と水酸基活性基とを単に用いた従来の低水素濃度の低圧活性種酸化方法では、ＯＮＯ膜の最上部のシリコン酸化膜１１０が、この下地のシリコン窒化膜１０８からシリコン原子を吸い上げて酸化膜が増大するので、シリコン窒化膜１１０が薄くなってしまい、設計通りのＯＮＯ膜構造が得られなくなる、といった問題があった。   Then, when forming the gate oxide film 112 (see FIG. 12B) of the peripheral circuit element during the formation of this element, an oxidation process is performed to form the gate oxide film 112. Then, an electrode formation process is performed to form a second gate electrode 114 for a flash memory and a gate electrode 116 for a peripheral circuit element at the same time as shown in FIG. Here, when the oxidation treatment is performed in the step shown in FIG. 12B, the conventional low hydrogen concentration low pressure active species oxidation method using only oxygen active species and hydroxyl group active groups oxidizes silicon at the top of the ONO film. Since the film 110 sucks silicon atoms from the underlying silicon nitride film 108 to increase the oxide film, there is a problem that the silicon nitride film 110 becomes thin and the ONO film structure as designed cannot be obtained. .

本発明は、以上のような問題点に着目し、これを有効に解決すべく創案されたものである。本発明の目的は、表面に露出している異種材料の表面に対して十分な選択酸化処理を行うことができ、しかも、その膜厚の面間均一性も高く維持することが可能な被処理体の酸化方法、酸化装置及び記憶媒体を提供することにある。   The present invention has been devised to pay attention to the above problems and to effectively solve them. The object of the present invention is to perform sufficient selective oxidation treatment on the surface of a different kind of material exposed on the surface, and to maintain a high uniformity of the film thickness between the surfaces. An object of the present invention is to provide a body oxidation method, an oxidation apparatus, and a storage medium.

本発明者は、酸素活性種と水酸基活性種とを用いた低圧の選択酸化処理について鋭意研究した結果、酸化性ガスである酸素ガスの供給を反応途中で補給し、更に、還元性ガスである水素ガスの濃度を最適化することにより、選択酸化が可能となり、しかも膜厚の面間均一性も高く維持することができる、という知見を得ることにより、本発明に至ったものである。   As a result of earnest research on the low-pressure selective oxidation treatment using the oxygen active species and the hydroxyl active species, the present inventor replenished the supply of oxygen gas, which is an oxidizing gas, during the reaction, and is a reducing gas. By optimizing the concentration of hydrogen gas, selective oxidation is possible, and the in-plane uniformity of the film thickness can be maintained at a high level, thereby obtaining the present invention.

請求項１に係る発明は、所定の長さを有する真空引き可能になされた縦型の処理容器内にシリコン層とシリコン窒化層とが表面に露出している被処理体を前記処理容器の長さ方向に沿って多段に複数枚収容し、前記処理容器内に酸化性ガスと還元性ガスとを供給して前記両ガスを反応させることによって発生した酸素活性種と水酸基活性種とを有する雰囲気中で前記被処理体の表面を選択的に酸化するようにした被処理体の酸化方法において、酸化性ガス噴射ノズルのガス出口と還元性ガス噴射ノズルのガス出口とを前記処理容器の長手方向の一端側にそれぞれ位置させて、前記酸化性ガスと前記還元性ガスとを前記処理容器の長手方向の一端側よりそれぞれ供給して他端側に向けて流すと共に、前記処理容器の長手方向の途中に補助ノズルのガス噴射口を位置させて前記酸化性ガスを前記処理容器の長手方向の途中に補助的に供給するようにしたことを特徴とする被処理体の酸化方法である。
このように、酸化性ガスと還元性ガスとを処理容器の長手方向の一端側よりそれぞれ供給すると共に、酸化性ガスを処理容器の長手方向の途中に補助的に供給するようにしたので、シリコン層とシリコン窒化層との異種材料が表面に露出している被処理体に対して十分な選択酸化処理を行うことができ、しかも、形成される酸化膜の厚さの面間均一性も高く維持することができる。 Invention, the processing chamber to be processed body in which a silicon layer and a silicon nitride layer is exposed on the surface evacuable Ninasa the vertical processing barber vessel having a predetermined length according to claim 1 multistage houses several sheets double along the lengthwise, the active oxygen species and active hydroxyl species generated by supplying an oxidizing gas and a reducing gas reacting the two gases into the processing chamber In the method for oxidizing the object to be treated, which selectively oxidizes the surface of the object to be treated in an atmosphere having gas, a gas outlet of the oxidizing gas injection nozzle and a gas outlet of the reducing gas injection nozzle are connected to the processing container. longitudinal respectively is positioned on one end side, with flow toward the other side and the reducing gas and the oxidizing gas is fed subjected respectively than the longitudinal one end side of the processing chamber, the processing chamber Auxiliary nozzle in the middle of the longitudinal direction Is an oxidizing method of the object, characterized in that the oxidizing gas is positioned a gas injection port was such that auxiliary supply in the middle of the longitudinal direction of the processing container.
As described above, the oxidizing gas and the reducing gas are respectively supplied from one end side in the longitudinal direction of the processing container, and the oxidizing gas is supplementarily supplied in the longitudinal direction of the processing container. A sufficient selective oxidation treatment can be performed on the object whose surface is exposed to a different material between the layer and the silicon nitride layer, and the uniformity of the thickness of the formed oxide film is also high. Can be maintained.

この場合、例えば請求項２に規定するように、前記両ガスに対する前記還元性ガスの濃度は５０％〜１００％未満である。
また例えば請求項３に規定するように、前記処理容器内の被処理体の収容領域はその長手方向において少なくとも３つの領域に区画されており、前記各領域毎に前記酸化性ガスが補助的に供給される。
また例えば請求項４に規定するように、前記各領域毎に補助的に供給される酸化性ガスは、それぞれ供給の停止を含めて流量が独立的に制御される。 In this case, for example, as defined in claim 2, the concentration of the reducing gas with respect to the two gases is 50% to less than 100%.
Further, for example, as defined in claim 3, the storage region of the object to be processed in the processing container is partitioned into at least three regions in the longitudinal direction, and the oxidizing gas is supplementarily added to each region. Supplied.
Further, for example, as defined in claim 4, the flow rate of the oxidizing gas supplied supplementarily to each region is controlled independently including the stoppage of supply.

また例えば請求項５に規定するように、前記酸化性ガスはＯ２ とＮ２ ＯとＮＯとＮＯ２ とＯ３ よりなる群から選択される１つ以上のガスを含み、前記還元性ガスはＨ２ とＮＨ３ とＣＨ４ とＨＣｌと重水素よりなる群から選択される１つ以上のガスを含む。
請求項６に係る発明は、シリコン層とシリコン窒化層とが表面に露出している被処理体を所定のピッチで多段に複数枚支持する保持手段と、前記被処理体の表面を選択的に酸化処理するために前記保持手段を収容することができるように所定の長さを有すと共に真空引き可能になされた縦型の処理容器と、前記被処理体を加熱するための加熱手段と、前記処理容器の一端側に酸化性ガス噴射ノズルのガス出口を位置させて前記処理容器内の一端側へ酸化性ガスを供給する主酸化性ガス供給手段と、前記処理容器の一端側に還元性ガス噴射ノズルのガス出口を位置させて前記処理容器内の一端側へ還元性ガスを供給する還元性ガス供給手段と、前記処理容器内のガスの流れ方向の途中に補助ノズルのガス噴射口を位置させて前記処理容器内の長手方向の途中に酸化性ガスを供給する補助酸化性ガス供給手段と、を備えたことを特徴とする酸化装置である。 For example, as defined in claim 5, the oxidizing gas includes one or more gases selected from the group consisting of O 2 , N 2 O, NO, NO 2, and O 3 , and the reducing gas is It includes one or more gases selected from H 2 and NH 3, CH 4, HCl and the group consisting of deuterium.
According to a sixth aspect of the present invention, there is provided a holding means for supporting a plurality of objects to be processed, each having a silicon layer and a silicon nitride layer exposed on the surface, at a predetermined pitch , and a surface of the object to be processed selectively. A vertical processing container having a predetermined length and capable of being evacuated so that the holding means can be accommodated for oxidation, and a heating means for heating the object to be processed; a main oxidizing gas supply means for supplying an oxidizing gas into one end of the pre-Symbol processing container end side to position the gas outlet of the oxidizing gas injection nozzle of the processing chamber, reduced to one end of the processing vessel A reducing gas supply means for positioning a gas outlet of the reactive gas injection nozzle to supply a reducing gas to one end in the processing container, and a gas injection port of the auxiliary nozzle in the middle of the gas flow direction in the processing container the length of the pre-Symbol processing chamber by positioning the An auxiliary oxidizing gas supply means for supplying an oxidizing gas in the middle of the direction, an oxidation apparatus characterized by comprising a.

この場合、例えば請求項７に規定するように、前記補助酸化性ガス供給手段は、前記処理容器の長手方向の異なる位置にその先端部のガス噴射口が位置する複数の補助ノズルを有する。
この場合、例えば請求項８に規定するように、前記各補助ノズルからのガス供給量は、供給停止を含めてそれぞれ独立的に制御可能になされている。
この場合、例えば請求項９に規定するように、前記補助酸化性ガス供給手段は、前記処理容器の長手方向に沿って所定のピッチで複数のガス噴射口の形成された補助ノズルを有している。 In this case, for example, as defined in claim 7, the auxiliary oxidizing gas supply means has a plurality of auxiliary nozzles in which the gas injection ports at the distal ends thereof are located at different positions in the longitudinal direction of the processing container.
In this case, for example, as defined in claim 8, the gas supply amount from each of the auxiliary nozzles can be independently controlled including supply stop.
In this case, for example, as defined in claim 9, the auxiliary oxidizing gas supply means includes an auxiliary nozzle having a plurality of gas injection ports formed at a predetermined pitch along the longitudinal direction of the processing container. Yes.

この場合、例えば請求項１０に規定するように、前記ガス噴射口は、前記処理容器内の被処理体の収容領域をその長手方向において少なくとも３つの領域に区画した各領域に対応するように位置されている。
この場合、例えば請求項１１に規定するように、前記酸化性ガスはＯ２ とＮ２ ＯとＮＯとＮＯ２ とＯ３ よりなる群から選択される１つ以上のガスを含み、前記還元性ガスはＨ２ とＮＨ３ とＣＨ４ とＨＣｌと重水素よりなる群から選択される１つ以上のガスを含む。
請求項１２に係る発明は、シリコン層とシリコン窒化層とが表面に露出している被処理体を所定のピッチで多段に複数枚支持する保持手段と、前記被処理体の表面を選択的に酸化処理するために前記保持手段を収容することができるように所定の長さを有すと共に真空引き可能になされた縦型の処理容器と、前記被処理体を加熱するための加熱手段と、前記処理容器の一端側に酸化性ガス噴射ノズルのガス出口を位置させて前記処理容器内の一端側へ酸化性ガスを供給する主酸化性ガス供給手段と、前記処理容器の一端側に還元性ガス噴射ノズルのガス出口を位置させて前記処理容器内の一端側へ還元性ガスを供給する還元性ガス供給手段と、前記処理容器内のガスの流れ方向の途中に補助ノズルのガス噴射口を位置させて前記処理容器内の長手方向の途中に酸化性ガスを供給する補助酸化性ガス供給手段と、を備えた酸化装置を用い、前記処理容器内に酸化性ガスと還元性ガスとを供給して前記両ガスを反応させることによって発生した酸素活性種と水酸基活性種とを有する雰囲気中で前記被処理体の表面を選択的に酸化するようにして酸化処理を行なうに際して、前記酸化性ガスと前記還元性ガスとを前記処理容器の長手方向の一端側よりそれぞれ供給すると共に、前記酸化性ガスを前記処理容器の長手方向の途中に補助的に供給するように前記酸化装置を制御するプログラムを記憶することを特徴とする記憶媒体である。

In this case, for example, as defined in claim 10, the gas injection port is positioned so as to correspond to each region obtained by dividing the accommodation region of the object to be processed in the processing container into at least three regions in the longitudinal direction. Has been.
In this case, for example, as defined in claim 11, the oxidizing gas includes one or more gases selected from the group consisting of O 2 , N 2 O, NO, NO 2, and O 3 , and the reducing property. gas comprises one or more gases selected from H 2 and NH 3, CH 4, HCl and the group consisting of deuterium.
According to a twelfth aspect of the present invention, there is provided holding means for supporting a plurality of objects to be processed, each having a silicon layer and a silicon nitride layer exposed on the surface, at a predetermined pitch, and a surface of the object to be processed selectively. A vertical processing container having a predetermined length and capable of being evacuated so that the holding means can be accommodated for oxidation, and a heating means for heating the object to be processed; A main oxidizing gas supply means for supplying an oxidizing gas to one end side in the processing container by positioning a gas outlet of the oxidizing gas injection nozzle on one end side of the processing container, and a reducing property on one end side of the processing container A reducing gas supply means for positioning a gas outlet of the gas injection nozzle to supply a reducing gas to one end side in the processing container; and a gas injection port of the auxiliary nozzle in the middle of the gas flow direction in the processing container. Positioned in the processing vessel An auxiliary oxidizing gas supply means for supplying an oxidizing gas in the middle of the longitudinal direction, using an oxidation apparatus having a supplies an oxidizing gas and a reducing gas reacting the two gases into the processing chamber in by letting you selectively oxidizing the surface of the object to be treated in an atmosphere having the oxygen active species and active hydroxyl species generating an oxidation treatment by, and said reducing gas and said oxidizing gas A program for controlling the oxidizer so as to be supplied from one end side in the longitudinal direction of the processing container and to supply the oxidizing gas in the middle of the processing container in the longitudinal direction is stored. Storage medium.

本発明の被処理体の酸化方法、酸化装置及び記憶媒体によれば、次のように優れた作用効果を発揮することができる。
酸化性ガスと還元性ガスとを処理容器の長手方向の一端側よりそれぞれ供給すると共に、酸化性ガスを処理容器の長手方向の途中に補助的に供給するようにしたので、シリコン層とシリコン窒化層との異種材料が表面に露出している被処理体に対して十分な選択酸化処理を行うことができ、しかも、形成される酸化膜の厚さの面間均一性も高く維持することができる。 According to the oxidation method, the oxidation apparatus, and the storage medium of the object to be processed according to the present invention, the following excellent operational effects can be exhibited.
Since the oxidizing gas and the reducing gas are supplied from one end side in the longitudinal direction of the processing container, and the oxidizing gas is supplementarily supplied in the middle of the processing container in the longitudinal direction, the silicon layer and the silicon nitride It is possible to perform sufficient selective oxidation treatment on a target object whose surface is exposed to a material different from that of the layer, and to maintain high uniformity of the thickness of the oxide film to be formed. it can.

以下に、本発明に係る被処理体の酸化方法、酸化装置及び記憶媒体の一実施例を添付図面に基づいて詳述する。
図１は本発明方法を実施するための酸化装置の一例を示す構成図である。まずこの酸化装置について説明する。図示するように、この酸化装置２０は下端が開放されて上下方向に所定の長さを有して円筒体状になされた縦型の処理容器２２を有している。この処理容器２２は、例えば耐熱性の高い石英を用いることができる。
この処理容器２２の天井部には、開口された排気口２４が設けられると共に、この排気口２４に例えば直角に横方向へ屈曲された排気ライン２６が連設されている。そして、この排気ライン２６には、途中に圧力制御弁２８や真空ポンプ３０等が介設された真空排気系３２が接続されており、上記処理容器２２内の雰囲気を真空引きして排気できるようになっている。 Hereinafter, an embodiment of an oxidation method, an oxidation apparatus, and a storage medium for an object to be processed according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram showing an example of an oxidation apparatus for carrying out the method of the present invention. First, the oxidation apparatus will be described. As shown in the figure, the oxidizer 20 has a vertical processing container 22 having a cylindrical shape with a lower end opened and a predetermined length in the vertical direction. For example, quartz having high heat resistance can be used for the processing container 22.
An exhaust port 24 that is opened is provided in the ceiling portion of the processing vessel 22, and an exhaust line 26 that is bent at a right angle, for example, at right angles is connected to the exhaust port 24. The exhaust line 26 is connected to a vacuum exhaust system 32 having a pressure control valve 28, a vacuum pump 30 and the like interposed therebetween, so that the atmosphere in the processing vessel 22 can be evacuated and exhausted. It has become.

上記処理容器２２の下端は、例えばステンレススチール製の筒体状のマニホールド３４によって支持されており、このマニホールド３４の下方より多数枚の被処理体としての半導体ウエハＷを多段に所定のピッチで載置した保持手段としての石英製のウエハボート３６が昇降可能に挿脱自在になされている。上記処理容器２２の下端と上記マニホールド３４の上端との間には、Ｏリング等のシール部材３８が介在されて、この部分の気密性を維持している。本実施例の場合において、このウエハボート３６には、例えば５０枚程度の直径が３００ｍｍのウエハＷを略等ピッチで多段に支持できるようになっている。   The lower end of the processing container 22 is supported by a cylindrical manifold 34 made of, for example, stainless steel, and a plurality of semiconductor wafers W as processing objects are mounted at a predetermined pitch in multiple stages from below the manifold 34. A quartz wafer boat 36 as a holding means is placed so that it can be moved up and down. A sealing member 38 such as an O-ring is interposed between the lower end of the processing container 22 and the upper end of the manifold 34 to maintain the airtightness of this portion. In the case of the present embodiment, the wafer boat 36 can support, for example, about 50 wafers W having a diameter of 300 mm in multiple stages at a substantially equal pitch.

このウエハボート３６は、石英製の保温筒４０を介してテーブル４２上に載置されており、このテーブル４２は、マニホールド３４の下端開口部を開閉する蓋部４４を貫通する回転軸４６の上端部に支持される。そして、この回転軸４６の貫通部には、例えば磁性流体シール４８が介設され、この回転軸４６を気密にシールしつつ回転可能に支持している。また、蓋部４４の周辺部とマニホールド３４の下端部には、例えばＯリング等よりなるシール部材５０が介設されており、処理容器２２内の気密性を保持している。
上記した回転軸４６は、例えばボートエレベータ等の昇降機構５２に支持されたアーム５４の先端に取り付けられており、ウエハボート３６及び蓋部４４等を一体的に昇降できるようになされている。尚、上記テーブル４２を上記蓋部４４側へ固定して設け、ウエハボート３６を回転させることなくウエハＷの処理を行うようにしてもよい。 The wafer boat 36 is placed on a table 42 via a quartz heat insulating cylinder 40, and the table 42 has an upper end of a rotating shaft 46 that passes through a lid portion 44 that opens and closes a lower end opening of the manifold 34. Supported by the part. For example, a magnetic fluid seal 48 is interposed in the penetrating portion of the rotating shaft 46, and supports the rotating shaft 46 so as to be rotatable while hermetically sealing. Further, a seal member 50 made of, for example, an O-ring or the like is interposed between the peripheral portion of the lid portion 44 and the lower end portion of the manifold 34 to maintain the airtightness in the processing container 22.
The rotating shaft 46 is attached to the tip of an arm 54 supported by an elevating mechanism 52 such as a boat elevator, for example, so that the wafer boat 36 and the lid 44 can be moved up and down integrally. The table 42 may be fixedly provided on the lid 44 side, and the wafer W may be processed without rotating the wafer boat 36.

上記処理容器２２の側部には、これを取り囲むようにしてた例えば特開２００３−２０９０６３号公報に記載されたようなカーボンワイヤ製のヒータよりなる加熱手段５６が設けられており、この内側に位置する処理容器２２及びこの中の上記半導体ウエハＷを加熱し得るようになっている。このカーボンワイヤヒータは清浄なプロセスが実現でき、且つ昇降温特性に優れている。またこの加熱手段５６の外周には、断熱材５８が設けられており、この熱的安定性を確保するようになっている。そして、上記マニホールド３４には、各種のガスをこの処理容器２２内へ導入して供給するための各種のガス供給手段が設けられている。   A heating means 56 made of a carbon wire heater as described in, for example, Japanese Patent Application Laid-Open No. 2003-209063 is provided on the side of the processing container 22, and the inside thereof is provided inside the processing container 22. The processing container 22 positioned and the semiconductor wafer W therein can be heated. This carbon wire heater can realize a clean process and has excellent temperature rise and fall characteristics. Further, a heat insulating material 58 is provided on the outer periphery of the heating means 56 so as to ensure this thermal stability. The manifold 34 is provided with various gas supply means for introducing and supplying various gases into the processing container 22.

具体的には、このマニホールド３４には、上記処理容器２２内へ酸化性ガスを供給する主酸化性ガス供給手段６０及び補助酸化性ガス供給手段６２と、処理容器２２内へ還元性ガスを供給する還元性ガス供給手段６４とがそれぞれ設けられている。まず、上記主酸化性ガス供給手段６０と還元性ガス供給手段６４は、上記マニホールド３４の側壁を貫通させてその先端部を処理容器２２内の一端側である下部に挿入して臨ませて設けた酸化性ガス噴射ノズル６６及び還元性ガス噴射ノズル６８をそれぞれ有している。そして、各噴射ノズル６６、６８から延びるガス通路７０、７２の途中にはマスフローコントローラのような流量制御器７４、７６がそれぞれ介設されており、マイクロコンピュータ等よりなる主制御部７８により上記各流量制御器７４、７６をそれぞれ制御して各ガス流量を制御し得るようになっている。また、この主制御部７８は、この酸化装置２０の全体の動作も制御するものであり、後述するこの酸化装置２０の動作は、この主制御部７８からの指令によって行われる。この主制御部７８は、その動作制御を行なうためのプログラムが予め記憶されているフロッピディスクやフラッシュメモリ等の記憶媒体１００を有している。   Specifically, a main oxidizing gas supply unit 60 and an auxiliary oxidizing gas supply unit 62 for supplying an oxidizing gas into the processing vessel 22 and a reducing gas into the processing vessel 22 are supplied to the manifold 34. Reducing gas supply means 64 is provided. First, the main oxidizing gas supply means 60 and the reducing gas supply means 64 are provided by penetrating the side wall of the manifold 34 and inserting the front end of the main oxidizing gas supply means 60 and the reducing gas supply means 64 into a lower portion on one end side in the processing container 22. Each has an oxidizing gas injection nozzle 66 and a reducing gas injection nozzle 68. In the middle of the gas passages 70 and 72 extending from the injection nozzles 66 and 68, flow controllers 74 and 76 such as a mass flow controller are provided, respectively. The gas flow rate can be controlled by controlling the flow rate controllers 74 and 76, respectively. The main controller 78 also controls the overall operation of the oxidizer 20, and the operation of the oxidizer 20 described later is performed according to a command from the main controller 78. The main control unit 78 includes a storage medium 100 such as a floppy disk or a flash memory in which a program for controlling the operation is stored in advance.

また本発明の特徴とする補助酸化性ガス供給手段６２は、処理容器２２の長手方向の途中に酸化性ガスを補助的に供給するものであり、図示例では上記マニホールド３４の側壁を貫通させてその先端側をＬ字状に屈曲させて上方に延ばした複数本、例えば３本の補助ノズル８０Ａ、８０Ｂ、８０Ｃを有している。上記各補助ノズル８０Ａ〜８０Ｃから延びるガス通路８２Ａ、８２Ｂ、８２Ｃの途中には、マスフローコントローラのような流量制御器８４Ａ、８４Ｂ、８４Ｃ及び開閉弁８６Ａ、８６Ｂ、８６Ｃがそれぞれ介設されており、上記主制御部７８により補助的に供給する酸化性ガスの供給量を、供給の停止も含めてそれぞれ独立的に制御し得るようになっている。そして、上記各補助ノズル８０Ａ〜８０Ｃの先端部はガス噴射口８８Ａ、８８Ｂ、８８Ｃとして形成されており、各ガス噴射口８８Ａ〜８８Ｃは、上記処理容器２２の長手方向（上下方向）の途中においてそれぞれ異なる位置に設置されている。ここでは処理容器２２内のウエハＷの配列された収容領域Ｓをガスの流れ方向に沿って例えば３つの領域、すなわち上流域Ｓ１と中流域Ｓ２と下流域Ｓ３とに区画し、各流域Ｓ１〜Ｓ３に、上記ガス噴射口８８Ａ〜８８Ｃをそれぞれ位置させている。   The auxiliary oxidizing gas supply means 62, which is a feature of the present invention, supplies auxiliary oxidizing gas in the middle of the processing vessel 22 in the longitudinal direction. In the illustrated example, the auxiliary oxidizing gas supply means 62 penetrates the side wall of the manifold 34. A plurality of, for example, three auxiliary nozzles 80A, 80B, and 80C, which have their distal ends bent in an L shape and extended upward, are provided. In the middle of the gas passages 82A, 82B and 82C extending from the auxiliary nozzles 80A to 80C, flow controllers 84A, 84B and 84C such as a mass flow controller and on-off valves 86A, 86B and 86C are interposed, respectively. The supply amount of the oxidizing gas that is supplementarily supplied by the main control unit 78 can be independently controlled including the stop of supply. And the front-end | tip part of each said auxiliary nozzle 80A-80C is formed as gas injection port 88A, 88B, 88C, and each gas injection port 88A-88C is in the middle of the longitudinal direction (up-down direction) of the said processing container 22. They are installed at different positions. Here, the accommodation region S in which the wafers W in the processing container 22 are arranged is divided into, for example, three regions, that is, an upstream region S1, a middle flow region S2, and a downstream region S3 along the gas flow direction. In S3, the gas injection ports 88A to 88C are respectively positioned.

具体的には、上記処理容器２２内のウエハＷが収容される空間を収容領域Ｓとしており、図示例では処理容器２２内へ導入されたガスは、この導入された位置より収容領域Ｓ内を上方向に向かって流れて上端部に設けた排気口２４から排出される。そして、この収容領域Ｓは、ウエハボート３６の長さよりも僅かに上下方向に広く設定されており、ガスの流れ方向に沿って便宜上、３つの領域、すなわち上流域Ｓ１（図中において下部の領域）、中流域Ｓ２（図中において中央の領域）、下流域Ｓ３（図中において上部の領域）に区分されている。例えば最も短い補助ノズル８０Ａのガス噴射口８８Ａを上流域Ｓ１に位置させている。より詳しくは、このガス噴射口８８Ａは、ウエハボート３６の下端部の近傍に位置させるのがよい。   Specifically, a space in which the wafer W in the processing container 22 is stored is defined as a storage area S. In the illustrated example, the gas introduced into the processing container 22 passes through the storage area S from the introduced position. It flows upward and is discharged from an exhaust port 24 provided at the upper end. The accommodation area S is set to be slightly wider in the vertical direction than the length of the wafer boat 36. For convenience, the three areas, that is, the upstream area S1 (the lower area in the figure) are arranged along the gas flow direction. ), A middle flow area S2 (a central area in the figure), and a downstream area S3 (an upper area in the figure). For example, the gas injection port 88A of the shortest auxiliary nozzle 80A is positioned in the upstream region S1. More specifically, the gas injection port 88 </ b> A is preferably positioned in the vicinity of the lower end portion of the wafer boat 36.

また補助ノズル８０Ｂのガス噴射口８８Ｂは、中流域Ｓ２の略中央部に位置させ、最長の補助ノズル８０Ｃのガス噴射口８８Ｃは、下流域Ｓ３であってウエハボート３６の上端部よりも僅かな距離だけ下方に位置させるのがよい。尚、これらの各領域の区画は単なる一例であって、これよりも少なく、或いは多く区画するようにしてそれぞれの領域に対応させて補助ノズルを設けるようにしてもよい。ここでは一例として酸化性ガスとしてはＯ２ ガスが用いられ、還元性ガスとしてはＨ２ ガスが用いられている。また図示されてないが、必要に応じてＮ２ ガス等の不活性ガスを供給する不活性ガス供給手段も設けられている。 Further, the gas injection port 88B of the auxiliary nozzle 80B is positioned at a substantially central portion of the middle flow area S2, and the gas injection port 88C of the longest auxiliary nozzle 80C is in the downstream area S3 and slightly smaller than the upper end of the wafer boat 36. It is better to position it below the distance. Note that the divisions of these regions are merely examples, and auxiliary nozzles may be provided corresponding to the respective regions so that there are fewer or more divisions. Here, as an example, O 2 gas is used as the oxidizing gas, and H 2 gas is used as the reducing gas. Although not shown, the inert gas supply means for supplying an inert gas such as N 2 gas as required is also provided.

次に、以上のように構成された酸化装置２０を用いて行なわれる酸化方法について説明する。以下に説明する酸化装置２０の動作は、前述したように記憶媒体１００に記憶されているプログラムに基づいて動作する主制御部１００からの指令によって行われる。
まず、例えばシリコンウエハよりなる半導体ウエハＷがアンロード状態で酸化装置２０が待機状態の時には、処理容器２２はプロセス温度より低い温度に維持されており、常温の多数枚、例えば５０枚のウエハＷが載置された状態のウエハボート３６をホットウォール状態になされた処理容器２２内にその下方より上昇させてロードし、蓋部４４でマニホールド３４の下端開口部を閉じることにより処理容器２２内を密閉する。この半導体ウエハＷの表面には、前述したようにシリコン層とシリコン窒化層とが予めパターン化されて共に露出している。尚、シリコン層とはシリコン基板の表面自体も含むものとする。 Next, an oxidation method performed using the oxidation apparatus 20 configured as described above will be described. The operation of the oxidizer 20 described below is performed by a command from the main control unit 100 that operates based on a program stored in the storage medium 100 as described above.
First, when the semiconductor wafer W made of, for example, a silicon wafer is in an unloaded state and the oxidation apparatus 20 is in a standby state, the processing vessel 22 is maintained at a temperature lower than the process temperature. Is loaded into the processing vessel 22 in the hot wall state by raising the wafer boat 36 from below and closing the lower end opening of the manifold 34 with the lid 44. Seal. As described above, the silicon layer and the silicon nitride layer are previously patterned and exposed on the surface of the semiconductor wafer W together. The silicon layer includes the surface of the silicon substrate itself.

そして、処理容器２２内を真空引きして所定のプロセス圧力に維持すると共に、加熱手段５６への供給電力を増大させることにより、ウエハ温度を上昇させて酸化処理用のプロセス温度まで昇温して安定させ、その後、酸化処理工程を行なうに必要とされる所定の処理ガス、すなわちここではＯ２ ガスとＨ２ ガスとを流量制御しつつ各ガス供給手段６０、６２、６４の酸化性ガス噴射ノズル６６、補助ノズル８０Ａ〜８０Ｃ、及び還元性ガス噴射ノズル６８からそれぞれ処理容器２２内へ供給する。
この両ガスは処理容器２２内を上昇しつつ真空雰囲気下にて反応して水酸基活性種と酸素活性種とが発生し、この雰囲気が回転しているウエハボート３６に収容されているウエハＷと接触してウエハ表面に対して選択的に酸化処理が施されることになる。すなわち、シリコン層上には厚くＳｉＯ２ の酸化膜が形成され、シリコン窒化層上には薄くＳｉＯ２ の酸化膜が形成される。そして、この処理ガス、或いは反応により生成したガスは処理容器２２の天井部の排気口２４から系外へ排気されることになる。 Then, the inside of the processing container 22 is evacuated and maintained at a predetermined process pressure, and the power supplied to the heating means 56 is increased to raise the wafer temperature to the oxidation process temperature. Oxidizing gas injection of each gas supply means 60, 62, 64 while controlling the flow rate of a predetermined processing gas, that is, O 2 gas and H 2 gas here, which is required to stabilize and thereafter perform the oxidation treatment process The nozzle 66, the auxiliary nozzles 80A to 80C, and the reducing gas injection nozzle 68 are supplied into the processing container 22, respectively.
Both gases ascend in the processing vessel 22 and react in a vacuum atmosphere to generate hydroxyl active species and oxygen active species. The wafer W accommodated in the wafer boat 36 in which the atmosphere is rotating In contact with the wafer surface, the wafer surface is selectively oxidized. That is, a thick SiO 2 oxide film is formed on the silicon layer, and a thin SiO 2 oxide film is formed on the silicon nitride layer. The processing gas or the gas generated by the reaction is exhausted from the exhaust port 24 in the ceiling portion of the processing container 22 to the outside of the system.

この時のガス流量はＨ２ ガスが２００〜５０００ｓｃｃｍの範囲内で、例えば１８００ｓｃｃｍ、Ｏ２ ガスが５０〜１００００ｓｃｃｍの範囲内で、例えば４００ｓｃｃｍである。
上記酸化処理の具体的な流れは、上述のように、処理容器２２内へ別々に導入されたＯ２ ガスとＨ２ ガスは、ホットウォール状態となった処理容器２２内を上昇しつつウエハＷの直近で水素の燃焼反応を介して酸素活性種（Ｏ＊）と水酸基活性種（ＯＨ＊）とを主体とする雰囲気が形成されて、これらの活性種によってウエハＷの表面が酸化されてＳｉＯ２ 膜が形成される。この時のプロセス条件は、ウエハ温度が４００〜１０００℃の範囲内、例えば９００℃、圧力は１３．３〜１３３０Ｐａの範囲内、例えば１３３Ｐａ（１Ｔｏｒｒ）である。また、処理時間は形成すべき膜厚にもよるが例えば１０〜３０分程度である。 The gas flow rate at this time is in the range of 200 to 5000 sccm for H 2 gas, for example, 1800 sccm, and in the range of 50 to 10,000 sccm for O 2 gas, for example, 400 sccm.
As described above, the specific flow of the oxidation process is as described above. The O 2 gas and the H 2 gas separately introduced into the processing container 22 are moved up in the processing container 22 in a hot wall state, and the wafer W An atmosphere mainly composed of oxygen active species (O *) and hydroxyl active species (OH *) is formed through a combustion reaction of hydrogen, and the surface of the wafer W is oxidized by these active species to form SiO. Two films are formed. The process conditions at this time are a wafer temperature in the range of 400 to 1000 ° C., for example, 900 ° C., and a pressure in the range of 13.3 to 1330 Pa, for example, 133 Pa (1 Torr). Further, the processing time is, for example, about 10 to 30 minutes although it depends on the film thickness to be formed.

ここで上記した活性種の形成過程は、次のように考えられる。すなわち、減圧雰囲気下にて水素と酸素とを別々にホットウォール状態の処理容器２２内へ導入することにより、ウエハＷの直近にて以下のような水素の燃焼反応が進行すると考えられる。尚、下記の式中において＊印を付した化学記号はその活性種を表す。
Ｈ２ ＋Ｏ２ → Ｈ＊＋ＨＯ２
Ｏ２ ＋Ｈ＊ → ＯＨ＊＋Ｏ＊
Ｈ２ ＋Ｏ＊ → Ｈ＊＋ＯＨ＊
Ｈ２ ＋ＯＨ＊ → Ｈ＊＋Ｈ２ Ｏ Here, the process of forming the active species is considered as follows. That is, it is considered that the following hydrogen combustion reaction proceeds in the immediate vicinity of the wafer W by separately introducing hydrogen and oxygen into the processing vessel 22 in a hot wall state under a reduced pressure atmosphere. In the following formula, chemical symbols marked with * represent active species.
H 2 + O 2 → H * + HO 2
O 2 + H * → OH * + O *
H 2 + O * → H * + OH *
H 2 + OH * → H * + H 2 O

このように、Ｈ２ 及びＯ２ を別々に処理容器２２内に導入すると、水素の燃焼反応過程中においてＯ＊（酸素活性種）とＯＨ＊（水酸基活性種）とＨ２ Ｏ（水蒸気）が発生し、これらによりウエハ表面が酸化されてＳｉＯ２ 膜が上述のように選択的に形成される。この時、特に上記Ｏ＊とＯＨ＊の両活性種が大きく作用するものと考えられる。ここで、本発明では、各補助ノズル８０Ａ〜８０Ｃを用いて収容領域Ｓの各領域、すなわち上流域Ｓ１、中流域Ｓ２、下流域Ｓ３に対してＯ２ ガスをそれぞれ必要量だけ供給しており、このＯ２ ガスが下方向より上昇してくるＨ２ ガスと順次反応して消費されて、或いは失活して不足気味になった酸素活性種や水酸基活性種がこれらを補うように作られる。従って、面間方向（高さ方向）においてウエハＷのどの高さ位置においても過不足のない活性種が存在するような状態となって活性種の濃度を均一にでき、シリコン層の表面に選択的に形成された酸化膜の膜厚の面間均一性を向上させることができる。この結果図１２に示したようなＯＮＯ膜のゲート構造において、シリコン窒化膜１０８が薄膜化されることを防止でき、設計通りのＯＮＯ膜構造を得ることができる。 As described above, when H 2 and O 2 are separately introduced into the processing vessel 22, O * (oxygen active species), OH * (hydroxyl active species), and H 2 O (water vapor) are generated during the hydrogen combustion reaction process. As a result, the wafer surface is oxidized and the SiO 2 film is selectively formed as described above. At this time, it is considered that both the active species O * and OH * act particularly greatly. Here, in the present invention, each auxiliary nozzle 80A to 80C is used to supply a necessary amount of O 2 gas to each region of the accommodation region S, that is, the upstream region S1, the middle flow region S2, and the downstream region S3. the O 2 gas is consumed sequentially reacting with H 2 gas coming rises from the lower direction, or deactivated activated oxygen becomes somewhat insufficient in and active hydroxyl species is made to compensate for these . Therefore, in the inter-plane direction (height direction), the active species can be made uniform in concentration so that active species without excess or deficiency exist at any height position of the wafer W, and selected on the surface of the silicon layer. Therefore, the uniformity of the thickness of the oxide film formed can be improved. As a result, in the gate structure of the ONO film as shown in FIG. 12, the silicon nitride film 108 can be prevented from being thinned, and the ONO film structure as designed can be obtained.

次に、Ｓｉ面（シリコン層）とＳｉＮ（シリコン窒化層）とが表面に露出しているシリコン基板のウエハに対して実際に選択酸化処理を施して、その時の水素ガス濃度やＯ２ ガスの供給態様の評価を行ったので、その評価結果について説明する。
＜評価１＞
まず評価１として、補助酸化性ガス供給手段６２を用いず（Ｏ２ ガスの供給はゼロ）、主酸化性ガス供給手段５０からＯ２ ガスを供給し、還元性ガス供給手段６４からＨ２ ガスを供給し、全ガス流量に対するＨ２ ガス濃度を変化させた時の酸化膜の厚さの関係を検討した。図２及び図３はその結果を示し、図２はＨ２ ガス濃度とＳｉＮ面／Ｓｉ面上の酸化膜の厚さとの関係を示すグラフ、図３は図２中のＳｉ面上の酸化膜の厚さ７ｎｍの時のＨ２ ガス濃度と膜厚の比（選択比）との関係を示すグラフである。
図２において、横軸はＳｉ面（シリコン層）上のＳｉＯ２ 膜の厚さを示し、縦軸はＳｉＮ面（シリコン窒化層）上のＳｉＯ２ 膜の厚さを示す。図３において、横軸はＨ２ ガス濃度［Ｈ２ ／（Ｈ２ ＋Ｏ２ ）］を示し、縦軸は酸化膜の膜厚比（ＳｉＮ面上／Ｓｉ面上）を示す。この時のプロセス条件は、プロセス温度が９００℃、プロセス圧力が４７Ｐａ（０．３５ｔｏｒｒ）、Ｈ２ ＋Ｏ２ ＝２．０Ｓｌｍ［スタンダードリットルパーミニッツ］（全ガス量）である。Ｈ２ ガス濃度は５％〜９０％まで変化させている。 Next, the silicon substrate wafer with the Si surface (silicon layer) and SiN (silicon nitride layer) exposed on the surface is actually subjected to selective oxidation treatment, and the hydrogen gas concentration and O 2 gas at that time Since the supply mode was evaluated, the evaluation result will be described.
<Evaluation 1>
First, as Evaluation 1, without using an auxiliary oxidizing gas supply means 62 (the supply of O 2 gas is zero), supplying O 2 gas from the main oxidizing gas supply means 50, H 2 gas from the reducing gas supply means 64 And the relationship of the thickness of the oxide film when the H 2 gas concentration was changed with respect to the total gas flow rate was examined. 2 and 3 show the results, FIG. 2 is a graph showing the relationship between the H 2 gas concentration and the thickness of the oxide film on the SiN surface / Si surface, and FIG. 3 is the oxide film on the Si surface in FIG. of a graph showing the relationship between the ratio of H 2 gas concentration and the thickness (selection ratio) when the thickness of 7 nm.
2, the horizontal axis represents the thickness of the SiO 2 film on the Si surface (silicon layer), and the vertical axis represents the thickness of the SiO 2 film on SiN surfaces (silicon nitride layer). In FIG. 3, the horizontal axis indicates the H 2 gas concentration [H 2 / (H 2 + O 2 )], and the vertical axis indicates the thickness ratio of the oxide film (on the SiN surface / on the Si surface). The process conditions at this time are a process temperature of 900 ° C., a process pressure of 47 Pa (0.35 torr), and H 2 + O 2 = 2.0 Slm [standard liter per minute] (total gas amount). The H 2 gas concentration is varied from 5% to 90%.

このグラフから明らかなように、Ｈ２ ガス濃度が低い、例えば５％程度の時でも酸化し易いＳｉ面上により多く選択的に酸化膜（ＳｉＯ２ ）が形成されているが、Ｈ２ ガス濃度を高くするに従って、図２中の直線の傾きが次第に小さくなってＳｉ面上により多くのＳｉＯ２ が形成されており、選択比が大幅に向上していることが確認できた。特に、図３に示すように膜厚比（選択比の逆数）を０．５５以下にするには、Ｈ２ ガス濃度を５０％以上に設定するのがよいことが確認できた。この場合、Ｈ２ ガス濃度が１００％の場合には、ウエハ表面は酸化されないので、その上限は１００％未満である。そして、実際には、酸化レートに基づくスループットを考慮すると、Ｈ２ ガス濃度は、好ましくは６６％〜９０％の範囲内がよく、この範囲では、高い選択比を維持しつつ、しかも高いスループットを確保することができることが確認できた。 As is apparent from this graph, H low 2 gas concentration, such as more selectively oxidized film by easily Si surface on oxidized even when about 5% (SiO 2) but is formed, H 2 gas concentration 2 was increased, the slope of the straight line in FIG. 2 was gradually reduced, so that more SiO 2 was formed on the Si surface, and it was confirmed that the selectivity was greatly improved. In particular, as shown in FIG. 3, it was confirmed that the H 2 gas concentration should be set to 50% or more in order to make the film thickness ratio (reciprocal of the selection ratio) 0.55 or less. In this case, when the H 2 gas concentration is 100%, the wafer surface is not oxidized, so the upper limit is less than 100%. Actually, considering the throughput based on the oxidation rate, the H 2 gas concentration is preferably in the range of 66% to 90%. In this range, a high throughput is maintained while maintaining a high selection ratio. It was confirmed that it could be secured.

しかしながら、上記の酸化処理時の場合は、選択比やスループットは十分に高くできるが、酸化膜の面間均一性はかなり低く、図４及び図５はその面間均一性について示すグラフである。図４及び図５は上記した酸化処理時における酸化膜の面間均一性を示すグラフであり、図４はＨ２ ガス濃度と膜厚の面間均一性との関係を示すグラフ、図５はウエハボート内の各位置における膜厚を示すグラフである。
図４の横軸はＨ２ ガス濃度を示し、縦軸は膜厚の面間均一性を示す。図４中にはＳｉ面上のＳｉＯ２ 膜の膜厚とＳｉＮ面上のＳｉＯ２ 膜の膜厚とがそれぞれ示されており、Ｈ２ ガス濃度が７０％以下までは膜厚の面間均一性は、共に８％以下を維持していたが、Ｈ２ ガス濃度が７０％以上では膜厚の面間均一性は共に大幅に向上して劣化しており、特にＨ２ ガス濃度が９０％では、Ｓｉ面上のＳｉＯ２ 膜の面間均一性は２０％程度まで上昇し、更にＳｉＮ面上のＳｉＯ２ 膜の面間均一性は３２％程度まで上昇してその特性が非常に劣化している。図５は図４中のＨ２ ガス濃度が９０％の時のウエハボート中の”ＢＴＭ”（ボトム）、”ＣＴＲ”（センタ）、”ＴＯＰ”（トップ）の各位置の各膜厚の実際の値を示している。尚、”ＢＴＭ”、”ＣＴＲ”、及び”ＴＯＰ”は図１中のウエハボート３６の下部位置、中央位置、上部位置をそれぞれ代表している。 However, in the case of the above oxidation treatment, the selectivity and throughput can be made sufficiently high, but the inter-surface uniformity of the oxide film is considerably low, and FIGS. 4 and 5 are graphs showing the inter-surface uniformity. 4 and 5 are graphs showing the inter-surface uniformity of the oxide film during the above-described oxidation treatment, FIG. 4 is a graph showing the relationship between the H 2 gas concentration and the inter-surface uniformity of the film thickness, and FIG. It is a graph which shows the film thickness in each position in a wafer boat.
The horizontal axis of FIG. 4 indicates the H 2 gas concentration, and the vertical axis indicates the inter-surface uniformity of the film thickness. FIG. 4 shows the film thickness of the SiO 2 film on the Si surface and the film thickness of the SiO 2 film on the SiN surface, respectively, and the film thickness is uniform between the surfaces until the H 2 gas concentration is 70% or less. However, when the H 2 gas concentration is 70% or more, the uniformity of the film thickness is greatly improved and deteriorated. In particular, the H 2 gas concentration is 90%. Then, the inter-surface uniformity of the SiO 2 film on the Si surface is increased to about 20%, and further, the inter-surface uniformity of the SiO 2 film on the SiN surface is increased to about 32%, and the characteristics are extremely deteriorated. ing. FIG. 5 shows the actual film thickness at each position of “BTM” (bottom), “CTR” (center), and “TOP” (top) in the wafer boat when the H 2 gas concentration in FIG. 4 is 90%. The value of is shown. Note that “BTM”, “CTR”, and “TOP” represent the lower position, the center position, and the upper position of the wafer boat 36 in FIG. 1, respectively.

図５に示すように、”ＢＴＭ”、”ＣＴＲ”、”ＴＯＰ”の各位置でそれぞれ膜厚が実際に大きく異なっており、膜厚の面間均一性が大きく劣化していることが確認できる。この膜厚の面間均一性を改善するためには、”ＴＯＰ”部分の膜厚を大きくする必要があることが認識できる。   As shown in FIG. 5, it can be confirmed that the film thickness actually differs greatly at each position of “BTM”, “CTR”, and “TOP”, and the uniformity of the film thickness is greatly deteriorated. . It can be recognized that in order to improve the inter-surface uniformity of the film thickness, it is necessary to increase the film thickness of the “TOP” portion.

＜評価２＞
上記図５に示す結果から、膜厚の面間均一性の向上を図るためには、上述のようにガス流の下流側である”ＴＯＰ”部分の膜厚を増加させればよいことが判明し、次にそのための対策について検討した。
ここではＨ２ ガス濃度に対するＳｉＯ２ 膜の膜厚の依存性を検討した。図６はＨ２ ガス濃度に対するＳｉＯ２ 膜の膜厚の依存性を示すグラフである。この時のプロセス条件は、Ｈ２ ガス濃度を５％〜９０％まで変化させており、それぞれ２０分間の酸化処理を行った時のＳｉＯ２ 膜の膜厚を示している。図示するように、Ｓｉ面上のＳｉＯ２ 及びＳｉＮ面上のＳｉＯ２ は、共にＨ２ ガス濃度が５０％以上の領域（図６中で破線で囲んで示す）では、Ｈ２ ガス濃度が高くなる程、膜厚が次第に小さくなってきており、従って、Ｈ２ ガス濃度が５０％以上の領域ではＨ２ ガス濃度が低い程、膜厚は大きく、すなわち酸化レートは高くなる。この結果、膜厚を上げたい領域にＯ２ ガスを供給してＨ２ ガス濃度を下げればよいことが認識できる。 <Evaluation 2>
From the results shown in FIG. 5, it is found that the film thickness of the “TOP” portion on the downstream side of the gas flow may be increased as described above in order to improve the uniformity of the film thickness between the surfaces. Next, we examined the countermeasures.
Here, the dependence of the SiO 2 film thickness on the H 2 gas concentration was examined. FIG. 6 is a graph showing the dependence of the SiO 2 film thickness on the H 2 gas concentration. The process conditions at this time indicate the film thickness of the SiO 2 film when the H 2 gas concentration is changed from 5% to 90% and oxidation treatment is performed for 20 minutes. As illustrated, SiO 2 on SiO 2 and SiN surfaces on Si surface, in both the H 2 gas concentration of 50% or more regions (shown enclosed by broken lines in FIG. 6), high H 2 gas concentration Accordingly, the film thickness is gradually reduced. Therefore, in the region where the H 2 gas concentration is 50% or more, the lower the H 2 gas concentration, the larger the film thickness, that is, the higher the oxidation rate. As a result, it can be recognized that the O 2 gas may be supplied to the region where the film thickness is desired to be increased to lower the H 2 gas concentration.

＜評価３＞
図６で示したように、膜厚を上げるには膜厚を上げたい領域にＯ２ ガスを供給してその領域のＨ２ ガス濃度を下げればよいことが認識できたので、ここでは図５において膜厚の小さい部分、すなわち”ＴＯＰ”の領域（ガス流の下流域Ｓ３）に補助的にＯ２ ガスを供給してその時の膜厚の変化を評価検討した。この検討結果を図７に示す。
図７は、ウエハボートの各位置におけるＳｉ面上のＳｉＯ２ 膜の膜厚の変化を示すグラフである。図７中において、梨地部分は基準値（図５中のＳｉ面上のＳｉＯ２ 膜の膜厚）を示し、斜線部分は今回のＯ２ ガスを補助的に供給した酸化処理の酸化膜の膜厚を示す。この評価の酸化処理時には、図１中において、ノズル６６、６８からＯ２ 、Ｈ２ ガスをそれぞれ供給すると共に、膜厚を大きくしたい領域である下流域Ｓ３（”ＴＯＰ”）に補助ノズル８０ＣからＯ２ ガスを供給している。この時のプロセス条件は、プロセス圧力、プロセス温度は、図５に示す場合と同じであり、ガス流量に関しては、Ｈ２ ガス流量が１．８ｓｌｍ、Ｏ２ ガス流量がノズル６６から０．２ｓｌｍ、補助ノズル８０Ｃから０．２ｓｌｍである。従って、Ｈ２ ガス濃度は８２％である。 <Evaluation 3>
As shown in FIG. 6, since it has been recognized that in order to increase the film thickness, it is sufficient to supply O 2 gas to a region where the film thickness is to be increased and to decrease the H 2 gas concentration in that region. Then, O 2 gas was supplementarily supplied to the portion having a small film thickness, that is, the “TOP” region (downstream region S3 of the gas flow), and the change in the film thickness at that time was evaluated and examined. The examination result is shown in FIG.
FIG. 7 is a graph showing changes in the thickness of the SiO 2 film on the Si surface at each position of the wafer boat. In FIG. 7, the satin portion indicates a reference value (the thickness of the SiO 2 film on the Si surface in FIG. 5), and the shaded portion indicates the oxide film film of the oxidation treatment supplementarily supplied with the O 2 gas this time. Indicates thickness. In the oxidation process of this evaluation, in FIG. 1, the O 2 and H 2 gases are supplied from the nozzles 66 and 68, respectively, and the downstream nozzle S3 (“TOP”), which is the area where the film thickness is desired to be increased, is supplied from the auxiliary nozzle 80C. O 2 gas is supplied. The process conditions at this time are the same as the process pressure and the process temperature shown in FIG. 5. Regarding the gas flow rate, the H 2 gas flow rate is 1.8 slm, the O 2 gas flow rate is 0.2 slm from the nozzle 66, The auxiliary nozzle 80C is 0.2 slm. Therefore, the H 2 gas concentration is 82%.

図７から明らかなように、”ＴＯＰ”の領域にＯ２ ガスを補助的に供給しただけで、この部分における膜厚は”２．５３ｎｍ”から”８．７０ｎｍ”へ略３．４倍も増加しており、従って、この部分に僅かなＯ２ ガスを補助的に供給するだけで膜厚の面間均一性を改善できることが確認できた。ここで注目すべき点は、”ＴＯＰ”の領域にＯ２ ガスを補助的に供給すると、この部分よりもガス流の上流側である”ＣＴＲ”や”ＢＴＭ”の部分も膜厚がある程度大きくなっている。この理由は、Ｏ２ ガスが処理容器内のガス流の流れに逆らって逆拡散して行ったものと考えられる。
以上の結果より、ノズル６６、６８からＯ２ ガス、Ｈ２ ガスをそれぞれ供給すると同時に、処理容器２２内のガス流方向の途中において、少なくとも一箇所からＯ２ ガスを供給することにより、好ましくは膜厚が最も小さくなる領域の部分にＯ２ ガスを供給することにより、膜厚の面間均一性を改善できることが判明した。 As is clear from FIG. 7, the film thickness in this portion is about 3.4 times from “2.53 nm” to “8.70 nm” only by supplementarily supplying O 2 gas to the “TOP” region. Therefore, it was confirmed that the uniformity of the film thickness can be improved only by supplementarily supplying a small amount of O 2 gas to this portion. It should be noted here that when O 2 gas is supplementarily supplied to the “TOP” region, the “CTR” and “BTM” portions upstream of the gas flow are also somewhat thicker than this portion. It has become. The reason for this is considered that the O 2 gas was reversely diffused against the gas flow in the processing container.
From the above results, it is preferable to supply O 2 gas and H 2 gas from the nozzles 66 and 68 and simultaneously supply O 2 gas from at least one place in the middle of the gas flow direction in the processing container 22. It has been found that by supplying O 2 gas to the portion of the region where the film thickness is the smallest, the uniformity of the film thickness can be improved.

＜評価４＞
さて、以上のように、処理容器２２内のガス流れ方向の途中にＯ２ ガスを補助的に供給することにより膜厚の面間均一性を改善できることが判明したので、ここではＯ２ ガスの供給形態の最適化を図る検討を行った。この供給形態の検討では、先に説明した図１に示す酸化装置を用いており、この検討結果を図８に示す。図８はＯ２ ガスの補助的な供給形態を最適化した時のウエハボートの各位置におけるＳｉ面上のＳｉＯ２ 膜の膜厚の変化を示すグラフである。図８中において、梨地部分は基準値（図５中のＳｉ面上のＳｉＯ２ 膜の膜厚）を示し、斜線部分は今回のＯ２ ガスを補助的な供給を最適化した酸化処理の酸化膜の膜厚を示す。この評価の酸化処理時には、図１中において、ノズル６６、６８からＯ２ 、Ｈ２ ガスをそれぞれ供給すると共に、各補助ノズル８０Ａ〜８０Ｃからそれぞれ所定の流量でＯ２ ガスを供給している。この時のプロセス条件は、プロセス圧力、プロセス温度は図５及び図７に示す場合と同じであり、ガス流量に関しては、Ｈ２ ガス流量が１．８ｓｌｍ、ノズル６６からは０．２ｓｌｍであって、この点は図７に示す場合であり、更にＯ２ ガスを各補助ノズル８０Ａ、８０Ｂ、８０Ｃから、０．０３ｓｌｍ、０．０１ｓｌｍ０．０１ｓｌｍの流量でそれぞれ供給している。従ってＨ２ ガス濃度は８８％である。 <Evaluation 4>
Now, as described above, since it can improve the interplanar uniformity of the film thickness was found by supplementary supply of O 2 gas in the middle of the gas flow direction in the processing vessel 22, wherein the O 2 gas A study to optimize the supply form was conducted. In the examination of the supply form, the above-described oxidation apparatus shown in FIG. 1 is used, and the examination result is shown in FIG. FIG. 8 is a graph showing changes in the film thickness of the SiO 2 film on the Si surface at each position of the wafer boat when the O 2 gas auxiliary supply mode is optimized. In FIG. 8, the satin portion indicates the reference value (the thickness of the SiO 2 film on the Si surface in FIG. 5), and the shaded portion indicates the oxidation of the oxidation process optimized for the supplementary supply of the O 2 gas. The film thickness is shown. In the oxidation process of this evaluation, in FIG. 1, O 2 and H 2 gases are supplied from nozzles 66 and 68, respectively, and O 2 gas is supplied at a predetermined flow rate from each of auxiliary nozzles 80A to 80C. The process conditions at this time are the same as those shown in FIGS. 5 and 7 for the process pressure and the process temperature. Regarding the gas flow rate, the H 2 gas flow rate is 1.8 slm and the nozzle 66 is 0.2 slm. This point is the case shown in FIG. 7, and O 2 gas is further supplied from the auxiliary nozzles 80A, 80B, and 80C at flow rates of 0.03 slm, 0.01 slm, and 0.01 slm, respectively. Therefore, the H 2 gas concentration is 88%.

図８から明らかなように、”ＢＴＭ”、”ＣＴＲ”及び”ＴＯＰ”の全領域において膜厚は４．１１〜４．１２ｎｍの範囲内になっており、酸化膜の膜厚の面間均一性を大幅に向上できることを、確認することができた。ここで、ガス流の最下流である”ＴＯＰ”の領域に、メインのノズル６６からの１／２０の流量である０．２ｓｌｍという僅かな流量のＯ２ ガスを加えても膜厚の面間均一性を向上できるのは、図７において説明した通りである。また各補助ノズル８０Ａ〜８０ＣからのＯ２ ガスの供給量は、供給の停止も含めてそれぞれ独立的に制御でき、ウエハＷの表面状態によって適宜増減する。ここで説明した各評価における酸化処理では、簡単なパターンのウエハを用いたが、実際の製品ウエハでは表面に多様なパターンが形成されているのでその表面積が非常に大きくなって活性種の消費もその分、多くなる。また、酸化処理すべきウエハ枚数も異なって活性種の消費量も変化する場合もある。このように処理容器２２内へ収容されたウエハの全表面積の相異に応じて、すなわちローディング効果の相異に応じて各補助ノズル８０Ａ〜８０Ｃより供給するＯ２ ガスの流量をそれぞれ最適化して供給する。 As is clear from FIG. 8, the film thickness is in the range of 4.11 to 4.12 nm in all the regions of “BTM”, “CTR”, and “TOP”, and the thickness of the oxide film is uniform between the surfaces. It was confirmed that the performance can be improved significantly. Here, even if O 2 gas having a slight flow rate of 0.2 slm, which is 1/20 flow rate from the main nozzle 66, is added to the “TOP” region which is the most downstream of the gas flow, The uniformity can be improved as described with reference to FIG. Further, the supply amount of O 2 gas from each of the auxiliary nozzles 80A to 80C can be controlled independently including the stoppage of supply, and is appropriately increased or decreased depending on the surface state of the wafer W. In the oxidation treatment in each evaluation described here, a wafer with a simple pattern was used. However, since various patterns are formed on the surface of an actual product wafer, the surface area becomes very large and the consumption of active species is also increased. It will increase by that much. In addition, the consumption of active species may vary depending on the number of wafers to be oxidized. In this way, the flow rate of O 2 gas supplied from each auxiliary nozzle 80A to 80C is optimized according to the difference in the total surface area of the wafers accommodated in the processing container 22, that is, according to the difference in loading effect. Supply.

上記実施例では、Ｏ２ ガスを補助的に供給する補助ノズルとしては、３本の補助ノズル８０Ａ〜８０Ｃを用いたが、これに限定されず、処理容器２２内のウエハボート３６の略全長をカバーできるような長さに設定された、図９に示すような１本の補助ノズル８０を設け、この補助ノズル８０に所定のピッチで複数のガス噴射口８８を分散させて設け、上流域Ｓ１〜下流域Ｓ３の全流域に亘ってＯ２ ガスを流量制御しつつ供給できるようにしてもよい。このような分散型の補助ノズル８０を用いた場合には、例えば上記各流域Ｓ１〜Ｓ３に対応させてガス噴射口８８の各口径を異ならせることにより、各流域毎のＯ２ ガスの流量を異ならせることができる。 In the above embodiment, the three auxiliary nozzles 80A to 80C are used as auxiliary nozzles for supplementarily supplying the O 2 gas. However, the auxiliary nozzles 80A to 80C are not limited to this. One auxiliary nozzle 80 as shown in FIG. 9 set to a length that can be covered is provided, and a plurality of gas injection ports 88 are provided in this auxiliary nozzle 80 in a dispersed manner at a predetermined pitch. The O 2 gas may be supplied while controlling the flow rate over the entire downstream area S3. When such a distributed auxiliary nozzle 80 is used, the flow rate of O 2 gas for each basin is changed by, for example, varying the diameters of the gas injection ports 88 corresponding to the basins S1 to S3. Can be different.

また図１に示す装置例にあっては、主（メイン）たるＯ２ ガス及びＨ２ ガスは、処理容器２２の下部側より供給し、この処理容器２２内で上方に向かうガス流を形成し、この容器の天井部の排気口２４より容器外へ排出するようにした構造となっているが、これに限定されず、図１０に示すような構造としてもよい。図１０は酸化装置の変形例を示す概略構成図である。すなわち、図１０に示す場合には、主たるＯ２ ガス及びＨ２ ガスを供給するノズル６６、６８をそれぞれ処理容器２２の内壁に沿って上方に向けて配設し、各ガス噴射口を容器天井部に配置している。そして、排気口２４を容器天井部ではなく、容器下部の側壁に設け、図１の場合とは逆に、処理容器２２内に上方より下方に向かうガス流を形成するようになっている。 Further, in the apparatus example shown in FIG. 1, main O 2 gas and H 2 gas are supplied from the lower side of the processing container 22 to form a gas flow upward in the processing container 22. Although the structure is such that the container is discharged from the exhaust port 24 in the ceiling of the container, the structure is not limited to this, and a structure as shown in FIG. FIG. 10 is a schematic configuration diagram showing a modification of the oxidation apparatus. That is, in the case shown in FIG. 10, nozzles 66 and 68 for supplying main O 2 gas and H 2 gas are arranged upward along the inner wall of the processing vessel 22, and each gas injection port is arranged on the vessel ceiling. Placed in the department. And the exhaust port 24 is provided not on the container ceiling but on the side wall of the lower part of the container, and in contrast to the case of FIG.

この図１０に示す場合には、図１中で示した上流域Ｓ３と下流域Ｓ１との関係が上下逆様になり、また、各補助ノズル８０Ａ〜８０Ｃからのガス供給形態は、図１中で示した場合とは上下逆様になるのは勿論である。
また、上記実施例では酸化性ガスとしてＯ２ ガスを用いたが、これに限定されず、Ｎ２ Ｏガス、ＮＯガス、ＮＯ２ ガス等を用いてもよい。また上記実施例では還元性ガスとしてＨ２ ガスを用いたが、これに限定されず、ＮＨ３ ガスやＣＨ４ ガスやＨＣｌガスを用いてもよい。
また、本発明は、被処理体としては、半導体ウエハに限定されず、ＬＣＤ基板、ガラス基板等にも適用することができる。 In the case shown in FIG. 10, the relationship between the upstream region S3 and the downstream region S1 shown in FIG. 1 is reversed upside down, and the gas supply form from each of the auxiliary nozzles 80A to 80C is as shown in FIG. Of course, it is upside down from the case shown in FIG.
In the above embodiment, using O 2 gas as the oxidizing gas is not limited thereto, N 2 O gas, NO gas may be used NO 2 gas. In the above embodiment has been with H 2 gas as the reducing gas is not limited thereto, may be used NH 3 gas and CH 4 gas and HCl gas.
Further, the present invention is not limited to a semiconductor wafer as an object to be processed, and can be applied to an LCD substrate, a glass substrate, and the like.

本発明方法を実施するための酸化装置の一例を示す構成図である。It is a block diagram which shows an example of the oxidation apparatus for implementing this invention method. Ｈ２ ガス濃度とＳｉＮ面／Ｓｉ面上の酸化膜の厚さとの関係を示すグラフである。It is a graph showing the relationship between the thickness of the oxide film on the H 2 gas concentration and the SiN surface / Si surface. 図２中のＳｉ面上の酸化膜の厚さ７ｎｍの時のＨ２ ガス濃度と膜厚の比（選択比）との関係を示すグラフである。3 is a graph showing the relationship between the H 2 gas concentration and the film thickness ratio (selection ratio) when the thickness of the oxide film on the Si surface in FIG. 2 is 7 nm. Ｈ２ ガス濃度と膜厚の面間均一性との関係を示すグラフである。It is a graph showing the relationship between the inter-plane uniformity of the H 2 gas concentration and the film thickness. ウエハボート内の各位置における膜厚を示すグラフである。It is a graph which shows the film thickness in each position in a wafer boat. Ｈ２ ガス濃度に対するＳｉＯ２ 膜の膜厚の依存性を示すグラフである。It is a graph showing the dependence of the film thickness of the SiO 2 film to H 2 gas concentration. ウエハボートの各位置におけるＳｉ面上のＳｉＯ２ 膜の膜厚の変化を示すグラフである。It is a graph showing the change in the film thickness of the SiO 2 film on the Si surface at the position of the wafer boat. Ｏ２ ガスの補助的な供給形態を最適化した時のウエハボートの各位置におけるＳｉ面上のＳｉＯ２ 膜の膜厚の変化を示すグラフである。O 2 is a graph showing changes in thickness of the SiO 2 film on the Si surface at the position of the wafer boat when optimizing an auxiliary supply form of gas. 補助ノズルの変形例を示す図である。It is a figure which shows the modification of an auxiliary nozzle. 酸化装置の変形例を示す概略構成図である。It is a schematic block diagram which shows the modification of an oxidation apparatus. 従来の酸化装置を示す概略構成図である。It is a schematic block diagram which shows the conventional oxidation apparatus. ＯＮＯ膜よりなるゲート構造を有する半導体集積回路の製造工程の一部を示す図である。It is a figure which shows a part of manufacturing process of the semiconductor integrated circuit which has a gate structure which consists of ONO films | membranes.

符号の説明Explanation of symbols

２０ 酸化装置
２２ 処理容器
３６ ウエハボート（保持手段）
５６ 加熱手段
６０ 主酸化性ガス供給手段
６２ 補助酸化性ガス供給手段
６４ 還元性ガス供給手段
６６ 酸化性ガス噴射ノズル
６８ 還元性ガス噴射ノズル
８０Ａ〜８０Ｃ 補助ノズル
８８Ａ〜８８Ｃ ガス噴射口
１１０ 記憶媒体
Ｗ 半導体ウエハ（被処理体）

20 Oxidizer 22 Processing vessel 36 Wafer boat (holding means)
56 heating means 60 main oxidizing gas supply means 62 auxiliary oxidizing gas supply means 64 reducing gas supply means 66 oxidizing gas injection nozzle 68 reducing gas injection nozzles 80A to 80C auxiliary nozzles 88A to 88C gas injection ports 110 storage medium W Semiconductor wafer (object to be processed)

Claims (12)

所定の長さを有する真空引き可能になされた縦型の処理容器内にシリコン層とシリコン窒化層とが表面に露出している被処理体を前記処理容器の長さ方向に沿って多段に複数枚収容し、前記処理容器内に酸化性ガスと還元性ガスとを供給して前記両ガスを反応させることによって発生した酸素活性種と水酸基活性種とを有する雰囲気中で前記被処理体の表面を選択的に酸化するようにした被処理体の酸化方法において、
酸化性ガス噴射ノズルのガス出口と還元性ガス噴射ノズルのガス出口とを前記処理容器の長手方向の一端側にそれぞれ位置させて、前記酸化性ガスと前記還元性ガスとを前記処理容器の長手方向の一端側よりそれぞれ供給して他端側に向けて流すと共に、前記処理容器の長手方向の途中に補助ノズルのガス噴射口を位置させて前記酸化性ガスを前記処理容器の長手方向の途中に補助的に供給するようにしたことを特徴とする被処理体の酸化方法。 Multistage along the workpiece that the silicon layer and the silicon nitride layer is exposed on the surface evacuable Ninasa the vertical processing barber vessel in the longitudinal direction of the processing container having a predetermined length the object to be treated in an atmosphere containing several sheets double, and an active oxygen species and active hydroxyl species generated by supplying an oxidizing gas and a reducing gas by reacting the two gases into the processing chamber to In the method for oxidizing a target object that selectively oxidizes the surface of the body,
A gas outlet of the oxidizing gas injection nozzle and a gas outlet of the reducing gas injection nozzle are respectively positioned at one end side in the longitudinal direction of the processing container, and the oxidizing gas and the reducing gas are placed in the longitudinal direction of the processing container. and each subjected fed from the direction of one end with flow toward the other end, the longitudinal direction of the longitudinal positions the gas injection port of the auxiliary nozzle in the middle and the oxidative gas in the processing chamber wherein the process chamber A method for oxidizing an object to be processed, characterized in that it is supplementarily supplied in the middle of the process. 前記両ガスに対する前記還元性ガスの濃度は５０％〜１００％未満であることを特徴とする請求項１に記載の被処理体の酸化方法。   The method for oxidizing an object to be processed according to claim 1, wherein the concentration of the reducing gas with respect to both the gases is 50% to less than 100%. 前記処理容器内の被処理体の収容領域はその長手方向において少なくとも３つの領域に区画されており、前記各領域毎に前記酸化性ガスが補助的に供給されることを特徴とする請求項１または２記載の被処理体の酸化方法。   The storage area of the object to be processed in the processing container is partitioned into at least three areas in the longitudinal direction, and the oxidizing gas is supplementarily supplied to each of the areas. Alternatively, the method for oxidizing an object to be treated according to 2. 前記各領域毎に補助的に供給される酸化性ガスは、それぞれ供給の停止を含めて流量が独立的に制御されることを特徴とする請求項３記載の被処理体の酸化方法。   4. The method for oxidizing an object to be processed according to claim 3, wherein the flow rate of the oxidizing gas supplied supplementarily to each region is controlled independently including the stopping of supply. 前記酸化性ガスはＯ２ とＮ２ ＯとＮＯとＮＯ２ とＯ３ よりなる群から選択される１つ以上のガスを含み、前記還元性ガスはＨ２ とＮＨ３ とＣＨ４ とＨＣｌと重水素よりなる群から選択される１つ以上のガスを含むことを特徴とする請求項１乃至４のいずれか一項に記載の被処理体の酸化方法。 The oxidizing gas includes one or more gases selected from the group consisting of O 2 , N 2 O, NO, NO 2, and O 3 , and the reducing gas includes H 2 , NH 3 , CH 4 , HCl, and the like. 5. The method for oxidizing an object to be processed according to claim 1, comprising at least one gas selected from the group consisting of deuterium. 6. シリコン層とシリコン窒化層とが表面に露出している被処理体を所定のピッチで多段に複数枚支持する保持手段と、
前記被処理体の表面を選択的に酸化処理するために前記保持手段を収容することができるように所定の長さを有すと共に真空引き可能になされた縦型の処理容器と、
前記被処理体を加熱するための加熱手段と、
前記処理容器の一端側に酸化性ガス噴射ノズルのガス出口を位置させて前記処理容器内の一端側へ酸化性ガスを供給する主酸化性ガス供給手段と、
前記処理容器の一端側に還元性ガス噴射ノズルのガス出口を位置させて前記処理容器内の一端側へ還元性ガスを供給する還元性ガス供給手段と、
前記処理容器内のガスの流れ方向の途中に補助ノズルのガス噴射口を位置させて前記処理容器内の長手方向の途中に酸化性ガスを供給する補助酸化性ガス供給手段と、
を備えたことを特徴とする酸化装置。 Holding means for supporting a plurality of objects to be processed, each having a silicon layer and a silicon nitride layer exposed on the surface, in a multi-stage at a predetermined pitch;
A vertical processing container having a predetermined length and capable of being evacuated so as to accommodate the holding means for selectively oxidizing the surface of the object to be processed;
Heating means for heating the object to be processed;
A main oxidizing gas supply means for supplying an oxidizing gas into one end of the pre-Symbol processing container end side to position the gas outlet of the oxidizing gas injection nozzle of the processing vessel,
Reducing gas supply means for positioning the gas outlet of the reducing gas injection nozzle on one end side of the processing container and supplying the reducing gas to one end side in the processing container;
An auxiliary oxidizing gas supply means for supplying a longitudinal middle oxidizing gas in the processing pre Symbol processing chamber to position the gas injection port of the auxiliary nozzles in the middle of the flow direction of the gas in the container,
An oxidation apparatus comprising: 前記補助酸化性ガス供給手段は、前記処理容器の長手方向の異なる位置にその先端部のガス噴射口が位置する複数の補助ノズルを有することを特徴とする請求項６記載の酸化装置。   7. The oxidizer according to claim 6, wherein the auxiliary oxidizing gas supply means has a plurality of auxiliary nozzles in which the gas injection ports at the front end portions thereof are located at different positions in the longitudinal direction of the processing container. 前記各補助ノズルからのガス供給量は、供給停止を含めてそれぞれ独立的に制御可能になされていることを特徴とする請求項７記載の酸化装置。   8. The oxidizer according to claim 7, wherein the gas supply amount from each auxiliary nozzle is independently controllable including supply stop. 前記補助酸化性ガス供給手段は、前記処理容器の長手方向に沿って所定のピッチで複数のガス噴射口の形成された補助ノズルを有していることを特徴とする請求項６乃至８のいずれか一項に記載の酸化装置。   9. The auxiliary oxidizing gas supply means includes an auxiliary nozzle having a plurality of gas injection ports formed at a predetermined pitch along the longitudinal direction of the processing vessel. An oxidizer according to claim 1. 前記ガス噴射口は、前記処理容器内の被処理体の収容領域をその長手方向において少なくとも３つの領域に区画した各領域に対応するように位置されていることを特徴とする請求項７乃至９のいずれか一項に記載の酸化装置。   10. The gas injection port is positioned so as to correspond to each region obtained by dividing an accommodation region of an object to be processed in the processing container into at least three regions in the longitudinal direction. The oxidation apparatus as described in any one of these. 前記酸化性ガスはＯ２ とＮ２ ＯとＮＯとＮＯ２ とＯ３ よりなる群から選択される１つ以上のガスを含み、前記還元性ガスはＨ２ とＮＨ３ とＣＨ４ とＨＣｌと重水素よりなる群から選択される１つ以上のガスを含むことを特徴とする請求項６乃至１０のいずれか一項に記載の酸化装置。 The oxidizing gas includes one or more gases selected from the group consisting of O 2 , N 2 O, NO, NO 2, and O 3 , and the reducing gas includes H 2 , NH 3 , CH 4 , HCl, and the like. The oxidizer according to any one of claims 6 to 10, comprising one or more gases selected from the group consisting of deuterium. シリコン層とシリコン窒化層とが表面に露出している被処理体を所定のピッチで多段に複数枚支持する保持手段と、
前記被処理体の表面を選択的に酸化処理するために前記保持手段を収容することができるように所定の長さを有すと共に真空引き可能になされた縦型の処理容器と、
前記被処理体を加熱するための加熱手段と、
前記処理容器の一端側に酸化性ガス噴射ノズルのガス出口を位置させて前記処理容器内の一端側へ酸化性ガスを供給する主酸化性ガス供給手段と、
前記処理容器の一端側に還元性ガス噴射ノズルのガス出口を位置させて前記処理容器内の一端側へ還元性ガスを供給する還元性ガス供給手段と、
前記処理容器内のガスの流れ方向の途中に補助ノズルのガス噴射口を位置させて前記処理容器内の長手方向の途中に酸化性ガスを供給する補助酸化性ガス供給手段と、を備えた酸化装置を用い、前記処理容器内に酸化性ガスと還元性ガスとを供給して前記両ガスを反応させることによって発生した酸素活性種と水酸基活性種とを有する雰囲気中で前記被処理体の表面を選択的に酸化するようにして酸化処理を行なうに際して、
前記酸化性ガスと前記還元性ガスとを前記処理容器の長手方向の一端側よりそれぞれ供給すると共に、前記酸化性ガスを前記処理容器の長手方向の途中に補助的に供給するように前記酸化装置を制御するプログラムを記憶することを特徴とする記憶媒体。 Holding means for supporting a plurality of objects to be processed, each having a silicon layer and a silicon nitride layer exposed on the surface, in a multi-stage at a predetermined pitch;
A vertical processing container having a predetermined length and capable of being evacuated so as to accommodate the holding means for selectively oxidizing the surface of the object to be processed;
Heating means for heating the object to be processed;
A main oxidizing gas supply means for supplying an oxidizing gas to one end side in the processing container by positioning a gas outlet of an oxidizing gas injection nozzle on one end side of the processing container;
Reducing gas supply means for positioning the gas outlet of the reducing gas injection nozzle on one end side of the processing container and supplying the reducing gas to one end side in the processing container;
An auxiliary oxidizing gas supply means for positioning the gas injection port of the auxiliary nozzle in the middle of the gas flow direction in the processing container and supplying the oxidizing gas in the middle of the longitudinal direction in the processing container; using the device, in front Symbol treatment active oxygen species generated by the reaction of the supplied both gas and oxidizing gas and a reducing gas into the container and an atmosphere having a hydroxyl active species of the object to be processed When performing oxidation treatment by selectively oxidizing the surface,
The oxidizing apparatus supplies the oxidizing gas and the reducing gas from one end side in the longitudinal direction of the processing container, and supplies the oxidizing gas in the middle of the processing container in the longitudinal direction. A storage medium for storing a program for controlling the computer.
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